2,6-Bis-(diethanolamino)-4-piperidino-pyrimido-[5,4-d] pyrimidine is disclosed in U.S. Pat. No. 3,322,755 to possess cardiovascular, spasmolytic, diuretic and CNS-stimulating properties. 1,2-Diphenyl-3,5-dioxo-4-(2-phenylsulfinyl-ethyl)-pyrazolidine (generic name: Sulfinpyrazone) is disclosed in Helv. Chim. Acta 44, 236 (1961) and has for a long time been used as an anti-gout agent. Both of these compounds were subsequently also found to have good antithrombotic properties [see Therapiewoche 26, 8464-8489 (1976)].
Both of these compounds individually, however, require relatively high dosages for achievement of an antithrombotic effect, where certain side-effects become noticeable; in the case of sulfinpyrazone these side-effects are stomach pains due to the ulcerogenic activity of this compound at high dosages.